Vladimir Putin said a war in Korea could be more devastating than the Chernobyl disaster - as Pyongyang was warned against another nuclear test.

The Russian President said he was "worried about the escalation on the Korean peninsula, because we are neighbours".

And Mr Putin, who also praised a US decision to postpone a planned missile test as part of efforts to reduce tensions, said he feared a situation worse than that in Chernobyl after a nuclear accident that was later linked to thousands of deaths.

"If, God forbid, something happens, Chernobyl which we all know a lot about, may seem like a child's fairy tale," he said.

"Is there such a threat or not? I think there is ... I would urge everyone to calm down ... and start to resolve the problems that have piled up for many years there at the negotiating table."

His intervention came after United Nations Secretary-General Ban Ki-moon urged the North not to carry out a new nuclear test - saying it would be a "provocative" act.

South Korea raised fears that a fourth test was due amid reports of increased activity at the main atomic test site Punggye-ri, but later backtracked.

Its Defence Ministry said: "We found there had been no unusual movements that indicated it wanted to carry out a nuclear test."

North Korea leader Kim Jong-Un

Mr Ban said: "The Democratic People's Republic of North Korea cannot go on like this, confronting and challenging the authority of the (UN) Security Council and the international community.

"I am urging them to refrain from taking any further provocative measures."

China's Foreign Ministry also said it wanted peace on the Korean peninsula, not war, adding a proper solution to the crisis was the responsibility of all parties.

The Pentagon has already strengthened its missile defences in response to the repeated threats made by Pyongyang in recent weeks.

However, the New York Times has reported that a more thorough plan - setting out a limited but forceful response to any future provocation - has been drawn up by the US and South Korea.

It said US officials had outlined a "counter-provocation" plan that would see a "response in kind" that would hit the source of any North Korean attack with similar weapons.

Meanwhile, North Korea said it was withdrawing all workers and suspending operations at its joint industrial zone with South Korea, the only surviving symbol of inter-Korean cooperation.

Video:N Korea: Hague Urges Calm Response

South Korea has appealed for North Korea to allow access to the Kaesong joint industrial park, six miles inside its borders.

The North has banned South Korean managers and personnel from crossing the border to enter the complex since last Wednesday.

So far 13 of the 123 South Korean firms operating there have been forced to halt production due to fuel and raw material shortages.